Oils consist of a complex mixture of hydrogen and carbon which is used for fuel, lubrication, plastics manufacturing, and many other purposes. These petroleum products get into water mainly by means of accidental spills from ships, tanker trucks, pipelines, and leaky underground storage tanks
Petroleum products affect surface water, impairing water quality with hydrocarbons, salts, nutrients, a host of organic compounds, and various heavy metals. Immediately after a spill, Oil slicks on the surface water producing a thick mousse. A large portion of the oil also forms emulsions or dissolves in the water. Some heavy portions will settle into to the bottom. Oxygen can be relatively easily obtained in the slick oil spill, but the nutrients are sometimes limited. In the warm waters of the equatorial and tropical oceans, it has been observed that this evaporation will remove as much as 40% of the spill during the first 24 hr.
Oil will also be oxidised by dissolved oxygen at the rate of 1 mg of oil per 3 mg of oxygen consumption. Microbial degradation will account for 2g of oil per square meter per day. Around 1% of the spilled oil will be dissolved or dispersed in water. In addition, photo-oxidation by solar radiation will also degrade a part of the oil. Thus, it can be expected that around 45-50% of any oil spill will be removed during the first 24 hr in the warm zone of the ocean. The heavier fractions of the spill will form drifting patches being split up by the prevailing winds and currents. These patches will ultimately end up as floating tar particles
Oil is an intimidating mixture of thousands of compounds, and every oil is different. All petroleum-based fuels, including the gasoline we pump into our cars, begin with crude oil that is pulled from the ground and processed at a refinery, where it is heated and separated into the different products we use. As crude oil is heated, lighter compounds evaporate and are collected and sold as gasoline, jet fuel, kerosene, diesel fuel, and lubricating oil (motor oil). Different types of oil have different environmental effects.
According to the National Oceanic and Atmospheric Administration (NOAA), scientists broadly categorize oil types into "light" and "heavy." When lighter oils, such as gas and diesel, spill out onto the water, they evaporate rather quickly and only remain in the environment for a short time. They are, however, highly toxic and highly flammable. Coming in contact with the oil or breathing the fumes can kill animals and plants. The oil can also ignite and explode. Heavier oils, such as those used to power ships, are not as toxic as light oils, but they can remain in the environment for years. They can harden after coming ashore, at which point they are less toxic to plants and animals. Heavy oil spills harm plants and animals by smothering them.
Chemical Constituents Commonly Found in oil spills Benzene| Colorless, sweet smelling liquid and vapor. Evaporates very quickly and dissolves slightly in water.| Toluene aka Methylbenzene| Toluene is a clear, colorless liquid and vapor that smells like gasoline. Toluene occurs naturally in crude oil.| Ethyl benzene| Ethyl benzene is a colorless liquid. It is highly flammable and smells like gasoline. It is naturally found in coal tar and petroleum.|
Generic alkanes(including octane,hexane, nonane)| Alkanes are colorless liquids or vapors that smell like gasoline. They are present in crude oil and petroleum products. They are highly flammable and evaporate easily| Xylene| Xylene is a colorless, sweet-smelling liquidand vapor. It is highly flammable and evaporates easily. It occurs naturally in petroleum and coal tar.
Amoco Cadiz and Exxon Valdez The Amoco Cadiz and Exxon Valdez oil spills caused much of the present interest--both from the public and the scientific community. Attention has been focused on the possible effects of oil spills on coastlines and benthic, neritic, and pelagic organisms. The problem of floating oil will increase with tanker traffic. But it is not the only source of problems. Rig blow-outs can create massive oil spills , and these rigs are usually near a coastal region. The presence of tar and oil slicks are the most conspicuous effects.
Tar may seriously soil beaches, and the clean-up may bring, as a secondary effect, beach erosion. Both oil and gas drilling and petroleum pollution affect water quality, accumulate in sediments, change the distribution of marine organisms, and cause illness to marine organisms and human beings--that is, similar effects as from inland waste disposal.
Effects to the water When oil gets in the water, hydrocarbons will linger on the surface and after time, some of them may be broken down or evaporate, but they all won't go away (Rice, 1984). Looking in the sediment on the bottom of the water or looking closely at water you can still see its traces. Once it is in the water it is difficult to remove. Some studies claim that it has little impact on the environment.
However, during the 1989 Exxon Valdez Oil Spill, numerous studies made it apparent that hydrocarbons can cause great damage to the ecosystem. In fact, there are lasting effects that we are just starting to see. In Valdez, Alaska at the oil terminal, they have to pump out ballast water from boats and oil tankers which has to be treated to remove contaminants.
However, they use a treatment process which takes out 99% of hydrocarbons, but due to the large amount of ballast water being used (10-15 million gallons a day), a large amount of hydrocarbons are still being pumped into the ocean (Rice, 1984). This problem can be seen locally. The hydrocarbons found in oil released into our local harbor have the potential to cause the same harmful effects on the environment.
US Environmental Protection Agency EPA deployed field teams to collect a small number of samples of oily debris, tar balls, mousse oil and other petroleum waste products that have washed up on the shore or were present on the surface of the water along the Coasts. Preliminary results have only shown chemical constituents that are usually found in petroleum products and therefore typical health precautions should be taken. Samples were collected at multiple locations to determine the chemical makeup of the oil washing up on shorelines. Oil has been washing up in various physical forms and samples were taken accordingly of tarballs, weathered oil, oil mousse, and grease.
The oil from the Exxon Valdez has killed and injured many of the marine life in that area. Attempts to clean up an oil spill can indirectly harm some of the resources we are trying to protect. For example, using hot water or chemicals to remove oil can harm plants and animals, and simply sending a team of cleanup workers into an oiled area can trample sensitive organisms and mix oil more deeply into a beach. The experts who respond to oil spills must consider all of these potential problems when evaluating the trade-offs of how far to go in removing spilled oil.
Exxon Valdez Oil Spill Cleanup Methods on the Water Boom - It comes in many sizes, shapes, and types and is used primarily to deflect and/or collect oil. Burning - Fresh oil contains gases which are very volatile. By igniting these gases whole oil slicks can be reduced to tarry residue. Dispersants - It disperses. They are chemicals that break-up oil into smaller and smaller concentrations. Potentially into individual molecules.
Skimming - a mechanical system for removing oil from the surface. This process was created based on the reality that oil is lighter than water. It should be kept in mind that it is not the duty of the people living around this area that should be cleaning. But it is the oil companies’ responsibility to prevent spills and to clean them up when they happen.
Organisms affected by the contaminated water Oil spills are considered forms of pollution that gives highly adverse effects on the environment. These oil spills greatly affect animals and marine plants. You can also be exposed to crude oil if you live where there is an oil spill or leak nearby. You may be exposed to crude oil from an oil spill through tarballs at a beach or shoreline. Winds and waves can tear patches of spilled oil into smaller pieces called tarballs. Tarballs are small pieces of oil that are remnants of oil spills and can stick to rocks, sand, or marine animals. Oil contaminants may stick to the fur of pets, which can transfer the contamination to people. Exposure at work can occur through contact with the skin, ingestion, or breathing crude oil liquid, drops, or fumes.
Studies have shown that the environmental damage of oil spills are far greater than originally thought. The hydrocarbon in petroleum-based oil is able to negatively impact marine life at concentrations as low as one part per billion. The heavier components of crude oil such as polycyclic aromatic hydrocarbons cause the most damage. Although being less toxic then lighter components such as benzene and toluene, unlike these components they are not volatile and do not evaporate easily. The oil mixes deeply into pebbles or sandy beaches, and remains there for months or years. The chemicals include carbon dioxide, carbon monoxide, lead, nitrogen oxides, particulate matter, polycyclic aromatic hydrocarbons, sulfur dioxide , and volatile organic compounds.
Breathing in both ethylbenzene and benzene can cause cancer and reproductive effects, while breathing in n-hexane can damage the nervous system and usher in numbness in the extremities, muscular weakness, blurred vision, headaches, and fatigue. Exposure to crude oil may irritate the eyes, skin, and respiratory system. It may cause dizziness, rapid heart rate, headaches, confusion, and anemia. Prolonged skin contact with crude oil may cause skin reddening, edema, and burning of the skin. If you think your health has been affected by exposure to crude oil, contact your health care professional.
The oil also affects the plants under the sea, it forms a thick layer on the water surface, and this layer blocks out light and prevents gaseous exchange. When this happens, not only will the plants not be able to photosynthesise, animals underneath the affected area will find that the supply of oxygen slowly diminishes, and is unable to be continuously replenished by the environment. When plants cannot photosynthesise, they eventually die, leading to a vicious effect on the food chain, ultimately affecting all animals.
Animals such as Seabirds, Sea Otters, Killer Whales, and other marine life are also affected by this because oil spills causes blindness, hypothermia, inducing low body temperatures. Oil may also enter the lungs or livers of animals, in turn poisoning the animals. Animals
Oil spills affect small organisms living in the sea, such as plankton, and larval fish, as well as bottom-dwelling organisms like oysters, seaweed, mussels. When these organisms die due to the oil, this affects the food chain. Fish that prey on these animals will have difficulty finding food, and may die. This will in turn affect their predators and so on.
Prevention Avoid contact with the oil. Keep children and animals away from the spill. If possible, put a fence around the area and post a warning sign. Use a source of water upstream from the spill. Even if you have to walk a long way, it is worth it to prevent health problems. Where oil has spilled, rainwater may be the only safe water to drink. Avoid eating animals that live in water such as crabs, shrimp, and snails near the spill and areas downstream.
They soak up toxins like sponges. Avoid bathing in affected water. If somebody falls in the water, they should wash right away with strong soap and clean water. Notify neighbors, government officials, the press, and NGOs that are concerned about health and the environment. Teach people about the dangers of oil at schools and community gatherings. In conclusion, the dangers oil spills pose to the environment are numerous and highly dangerous, hence, greater effort should be taken to ensure such oil spills are minimized in the future.
Resources: http://geology.uprm.edu http://www.whoi.edu http://seagrant.uaf.edu http://drs.nio.org http://en.hesperian.org http://www3.imperial.ac.uk http://www.epa.gov http://www.bt.cdc.gov http://toxtown.nlm.nih.gov